[Lawrie]

Are the slots that the rollers work in different as well,
I know the advance curve is different,
from the ford service book
68
Dist deg adv @ Distributor rpm
0-to 1/2. 200
2-3/4 to 3-3/4. 400
7-1/2 to 8-1/2. 950
total WOT adv 19 to 21deg @1900
(timing set at 4 deg)

11a 0- to 1/2 200
6-1/2 to 8 400
10-1/2 to 12. 600
Total WOT adv 25 to 28 @ 3450

The shaft assy with the little plate that drives the weights are both different ,hence the 68 or 11a stamped on them,so is the disc that controls the curve via the vac brake
Lawrie